Cycling 3g tank

[Coz]

I set up my daughters 3g betta tank last night and dosed ammo to 1ppm and put in a whole used filter cartidge from my 50g tank. Just dropped filter in the tank. She has a small air operated filter on her tank. This am ammo was 0. So I suspect this tank will cycle quickly!

How long should I leave my filter in there? I'm assuming the bb is living on that filter. Obviously this is a fishless cycle

 

[armymp327]

i would leave the old filter in there for at least a month to ensure the BB takes hold on the filter that will stay in the tank.

 

[Fishanatic]

Yes. Don't forget to test the water. Gonna be a bit harder to do water changes, and schedule everything.